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If you have a battery and inverter that enables power in the event of a power cut, do you need anything done with the wiring to facilitate this - manual grid disconnecting switch for example?
there's some switchgear required to isolate you from the grid otherwise you risk making cabling live that the power company, and most importantly their workforce, think they've shut down prior to working on it.
manual grid disconnecting switch for example?
Manual would not be allowed, it would need to be automatic.
Apparently the cost to install is probably outweighs the benefit from a few short lived power cuts.
(I would imagine there's all sorts of hoops you need to jump through*)
* Or maybe not 🤷🏻♂️
Doesn't the Tesla battery offer this option. I wonder what switch gear that needs.
Manual is fine. Same as generators use....
It's a dual pole change over switch (disconnects your circuits from the grid before connecting them to the eps) needed from the EPS side of the inverter - if you want to power your house circuits OR a Tesla gateway which is automatic version.
Any set up needs a local earth.
I've not got a change over but I've not powered the house circuits off mine. I've put in a seperate EPs system with standalone earth and will just run extension cords to where ever I need it at powercut time....
Manual would not be allowed, it would need to be automatic.
My manual change over switch
You also need to check if your system relies on grid frequency to operate. The default is that they will turn off during a powercut, to ensure the grid can be isolated to be worked on.
Much easier just to have a genny and an extension lead for vital stuff such as fridge freezer, and perhaps your router/mobile phones if it's a local powercut and the mast/exchange is still operational/on backup power also.
Much easier just to have a genny and an extension lead for vital stuff such as fridge freezer, a
Tbh I didn't find it easier at all when I used to do that.
It was noisy. It meant I had to go outside.... Dig out the Genny. The Genny needed maintainance - it needed fuel . It needed run up once ever 6.months or so. The fuel needed rotating as it'd go off.
It was cheaper interms of capex but it's opex was much higher as was it's hassle.
We have a battery with grid tie. Power cut currently means out power goes out. The givenergy guy who came to fix a fault suggested they were coming up with a retrofit box that will do what the Tesla wall does and auto switch. Needless to say I got very interested but he refused more info other than 2023 could be a thing.
Ahhh, when I first moved here 20 years ago we had quite a lot of power cuts and as I worked from home with 3 or 4 employees this was not good.
I looked hard at sizeable generators (big diesels) but was told I'd need an automatic changeover switch - clearly not.
It was going to be spendy to put one in so I hesitated..... And then the electric co upgraded some equipment nearby and the power cuts all but stopped.
The good thing about a deisel generator is that the fuel takes a very long time to go off and, of course, it can run for a very long time.
A battery has a limited amount of power it can supply and thats it.
Trail_rat can you explain a little more for a Luddite? You have a solar set up on the grid but then have a manual work around for power when the grid goes down?
I have a grid tie inverter that if it loses grid stops supplying my grid tied circuits.
It switched to eps.
My eps is linked to a second fuse board with standalone earth
This circuit has some sockets attached in various places.
My solar still charges the batteries. We just need to be mindful of what's being used. I have 10kwh storage which is enough for normal use for 24 hours with no sun or much much longer on essentials (boiler -main fridge and lighting)
It works well and is considerably easier to live with than my old generator set up. - if bad storms are forecast in winter and I expect power cuts I just set the inverter to "backup mode" from my phone and it'll charge to a >85% and maintain it.
Only had one power cut longer than a few hours in the last year but would get 1-2 a year in the 1-2 day region previous. Dodged storm frank though neighbours were out for 5-7 days.
It also does something unique my generator could never do.....keeps the bills small. December's bill was 16.86. the amount of electric used in December equates to a bill of £88. I'm out all day. Last year that was lost power I exported at 4 pence and had to pay 16 pence to get back at night. (34pence this year)
It’s absolutely pointless adding an extra earth rod for an inverter. What are you attempting to achieve?
It doesn’t matter if an appliance develops an earth fault because there’s no potential difference between you and the ground if you touch it. On the other hand if you bond the inverter to ground via an earth rod, you’ve just supplied a fault for current to flow.
Providing the supply from the inverter is RCD protected and will trip on a DC fault (something goes spectacularly wrong with the solar or battery side) you’re probably safer with it in an IT configuration for short term emergency use.
Due to the way my inverter operates it falls under
Regulation 551.4.3.2.1 of BS 7671
The good thing about a deisel generator is that the fuel takes a very long time to go off and, of course, it can run for a very long time.
A battery has a limited amount of power it can supply and thats it.
Just what I was going to say. If you really have supply issues a diesel generator is going to work best if you have any significant outage but if the power cuts are usually short and your usage is low then the battery will be ok. It all depends on your situation.
I run my place like a glorified yacht or camper van. My solar and battery system is autonomous from the grid and runs my consumer usit to power the house. If there is not enough sun to keep the batteries topped up, or if I know I have to do something that will use all my power too quickly then I just manually throw a switch (same as Brunnep has) to switch the consumer unit over to mains, leaving the battery system isolated to charge in its' own good time. This is no different to connecting to shore power/site hook up or what you would do if you ran a generator in a true off grid situation. In Decemeber, which was the first full month of using this system, I ran exclusively off battery/solar for 17 days. January so far I have only needed to be on mains for 5 days so far. I think come April I will not need to use my switch again until November. The beuaty of a manual switch is you can check upcoming forecasts so as to optimise battery usage.
Welshfarmer, Mark, could you tell me briefly what your system comprises of (or point me to a thread where it has been discussed ?) Many thanks
The beuaty of a manual switch is you can check upcoming forecasts so as to optimise battery usage.
You can still look at forecasts and adjust the battery charging of an automatic system via an App...
If you check out this link and scroll down to section 7 "eample wiring diagram" that is very similar to my set up
https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom
HOWEVER, I run 4x 3.2 KWh batteries rather than 8x 2 KWh ones (same make though). And I am not connected to the mains using the ESS setup shown there (which is the automatic way to run a system). I have chosen not to do that for my own reasons so instead of the mains connecting to the Inverter/charger via ACin I use a changeover swithch which means the mains is either off, or going direct to my consumer unit. The main issue I have is that my solar array and inverter are too big and not approved for grid connection, hence keeping them away from any issues that going for Grid tie would cause (3.6 Kwh max allowed IIRC)
The main issue I have is that my solar array and inverter are too big and not approved for grid connection, hence keeping them away from any issues that going for Grid tie would cause (3.6 Kwh max allowed IIRC)
You could ask your DNO if you could connect but chances are they'll charge you handsomely for an email that says yes or no (potentially No if you're in a sparsely populated area.
Sounds like you're doing it sensibly.
It’s absolutely pointless adding an extra earth rod for an inverter. What are you attempting to achieve?
Equipotential Bonding
It doesn’t matter if an appliance develops an earth fault because there’s no potential difference between you and the ground if you touch it. On the other hand if you bond the inverter to ground via an earth rod, you’ve just supplied a fault for current to flow.
You are basing this on full electrical separation, combined with double insulation however if Barbie, sorry Trail Rat has an appliance with a metal enclosure that is connected either directly or indirectly to the DNOs supply then the reverse will happen and a potential will flow between the fault and the metal enclosure path to the DNOs star point.
It’s also worth considering that should it be quite likely the DNO supply is a TN-C derived system (PME) the loss of the CNE will cause further issues. Reg 551.4.3.2.1 of BS 7671 recognizes this threat of nips in the bud, in the same
way as it recognizes the threat in Part 7 "Special Installations" of the aforementioned.
The only way you could ensure this doesn't happen is by earth free local potential bonding, full electrical separation on within a non-conduction locations. OR have an invertor that will sense the fault in the same way the Mode 3 car chargers do.
@sharkbait. the whole valley is on a dead-end single phase spur and we are also a good 200m from the pole transformer on 25mm bare cable to the house via a 60 amp main fuse. Chances are less than zero they would let us export more than 3.5 Kw
@welshfarmer
Many thanks, I'll give that link a proper read when i have some time.
@welshfarmer 16A per phase at nominal volts - so 3.68kW in your case I think - without asking. if you do ask then it’s what the supply will take, and then you “may” start paying for reinforcement.
once Access SCR comes in you shouldn’t as a demand premises pay for reinforcement even for generation, so I’m guessing you might get up to say 12kW export or so.
PM me if you fancy talking any of that through. My credentials in this area are reasonably well known.
@welshfarmer - sounds like you could almost cut ties with the grid and save on the standing charge.
The givenergy guy who came to fix a fault suggested they were coming up with a retrofit box that will do what the Tesla wall does and auto switch. Needless to say I got very interested but he refused more info other than 2023 could be a thing.
A "giv-gateway" appears to have appeared on the givenergy Products page with a "coming soon" label, so he's right, but what "soon" means who knows...